Hydraulic circuit



Dec. 5, 1967 I E. A. ROESKE 3,356,032

' HYDRAUL-IC CIRCUIT Filed Jan. 13, 1966 2 Sheets-Sheet 1 Dec. 5, 1967 E. A. ROESKE 3,356,032

HYDRAULIC CIRCUIT Filed Jan. 13, 1966 2 Sheets-Sheet 8 United States Patent 3,356,032 HYDRAULIC CIRCUIT Eugene A. Roeske, St. Louis County, Mo., assignor to Emerson Electric Co., St. Louis County, Mo., a corporation of Missouri Filed Jan. 13, 1966, Ser. No. 520,323 3 Claims. (Cl. 103-42) ABSTRACT OF THE DISCLOSURE A rotary pump of the ring gear and pin-ion type, having an intake manifold, a discharge manifold, a land between the intake and discharge manifolds, a land between the discharge and intake manifolds, the pinion being contiguous the manifolds and lands for defining undulating cavities is a fixed pattern as the ring gear and pinion rotate, a conduit opening at one end into the path of the cavities through the face of the land contiguous the pinion between the intake and discharge manifolds and communicating at its other end media-tely with the discharge manifold, and an orifice communicating at one end with the conduit and at its other end with the discharge manifold so that hydraulic fluid from the discharge manifold moves through the orifice. The conduit opens through the land at such a position with respect to the discharge manifold that no cavity communicates simultaneously with the conduit and the discharge manifold.

Background of the invention This invention relates to hydraulic circuits of the type in which a rotary undulatory cavity type pump supplies an amount of liquid greater than the demand, so that a portion of the supplied liquid bypasses the delivery point. A typical system of this sort is an oil burner system wherein the pump has a greater capacity than the nozzle, so that, in operation, a portion of the pumped oil is returned to the storage tank through a pressure-regulating and bypass valve. This invention will be described as applied to such an oil burner system, but its utility is not limited thereto.

One common and persistent problem in the operation of undulatory cavity type pumps of which internal-external type gear pumps are an example is that of cavitation within the chambers, and of pulling air through the seal on the suction side of the pump.

One of the objects of this invention is to provide a hydraulic system, in which an undulatory cavity type pump is used, in which cavitation and the pulling of air through the suction side seal is minimized.

Another object of this invention is to provide such a system which is simple and economical to manufacture and which is dependable in use.

Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.

Summary of the invention In accordance with this invention, generally stated, a hydraulic system is provided which includes a rotary pump, with an intake manifold, a discharge manifold, a land between the intake and discharge manifolds, and rotating means contiguous manifolds and lands for defining undulating expanding and contracting cavities in a fixed pattern. A conduit is provided opening at one end through the contiguous face of the land between the intake and discharge manifolds and communicating at its other end with a source of hydraulic fluid at a pressure higher than the pressure within the intake manifold. The

3,356,032 Patented Dec. 5, 1967 land is wider than the minimum necessary to operate the expanding and contracting chambers. In the preferred embodiment, the other end of the conduit communicates mediately with the discharge manifold, and an orifice is provided communcating at one end with the conduit and at its other end with an area of low pressure compared with the pressure at the discharge manifold, so that hydraulic fluid from the discharge side of the pump but at a substantially sub-discharge pressure is circulated through the orifice. The conduit opening through the land is so positioned with respect to the discharge manifold that no cavity communicates simultaneously with the conduit opening and the discharge manifold.

In the preferred embodiment, the means for providing the undulating cavities includes an extremely toothed pinion and an internally toothed ring gear, with different numbers of teeth, of the usual internal-external gear type, the internal and external gears of which are exemplified by those shown in Brundage US Patents 2,898,862 and 2,956,506. In the former patent, the pump is of the side delivery type in which the intake and discharge manifolds are in a radial face contiguous the gears; in the latter patent, the intake and discharge manifolds are radially outward of the ring gear. Either of these arrangements may be used in the system of this invention, though the radial faced manifolds are preferred. The undulating cavities can also be defined by sliding vanes in an excentric or non-circular cavity, a Well known type of hydraulic pump.

The orifice can be arranged in series with the open mouth of the conduit, or it can be in parallel with the conduit. In any event, it provides a restricted passage between a high pressure area at the conduit mouth and a relatively low pressure area. The low pressure may be and preferably is provided by the intake manifold itself.

Brief description of the drawings In the drawing,

FIGURE 1 is a sectional view through a hydraulic system of this invention adapted for use in an oil burner, showing a hydraulic pump, an electric motor connected to drive the pump, and a combination pressure regulating and cut-off valve communicating with the pump;

FIGURE 2 is a view in end elevation, in the direction indicated by the line 2-2 of FIGURE 1, of the valve casing and part of its internal porting, with a cover plate removed;

FIGURE 3 is a sectional view taken along the line 3-3 of FIGURE 1;'

FIGURE 4 is a fragmentary sectional view corresponding to the view shown in FIGURE 3, but showing the internal and external gears of the hydraulic pump in slightly different positions with respect to intake and discharge manifolds;

FIGURE 5 is a fragmentary view in elevation in the direction indicated by the arrows 3-3 in FIGURE 1, but taken along the parting line between the motor and the valve casing; and

FIGURE 6 is a schematic view of still another embodiment of hydraulic system of this invention.

Description of the preferred embodiments Referring now to the drawing, and particularly to FIG- URE -6, for one illustrative embodiment of hydraulic system of this invention, reference numeral 1 indicates a hydraulic pump shown diagrammatically as consisting of an internal pinion 2, mounted on a shaft 3 driven by a source of power not here shown, and an external ring gear 4. The pinion 2 and the ring gear 4 define between them cavities 5 which undulate as the pinion and ring gear rotate, in a fixed pattern.

A fiat radial surface contiguous the pinion and ring gear has recessed into it, in a position to communicate with the cavities '5 through a portion of their travel, an intake manifold 6 and a discharge manifold 7. An uninterrupted area of the surface between the intake manifold 6 and the discharge manifold 7 constitutes a land 8. and an uninterrupted part of the surface between the discharge manifold 7 and the intake manifold 6 constitutes a land 9.

A reservoir 20, in this embodiment containing fuel oil, communicates, through an intake line 21, with an intake port 26 opening into the intake manifold 6.

A pressure regulating and cut off valve has a seat 31 with a passage 32 in it through which oil is delivered to a nozzle; a valve head 33, which, when no oil is being supplied the valve, seats against the seat 31; a piston 34, carrying the valve head 33 and closely but slidably mounted in a cylinder 35, and a pressure regulating spring 36, normally biasing the piston 34 toward the seat 31. A chamber 38 defined between the piston 34 and the seat 31, communicates through a discharge line 39, with a discharge port 37 in the discharge manifold 7.

A port 40 in the wall of the cylinder 35 is positioned to communicate progressively with the chamber 38 as the piston 34 moves downwardly past the mouth of the port. The port 40 communicates through a line 41 with a chamber 42 on the other axial side of the piston 34 from the seat 31; with a pump seal gland 43 and, through parallel branch conduits 44 and 45 with an inlet bleeder hole 46 in the intake manifold and a conduit opening 48 in the face of the land 8 contiguous the rotating members 2 and 4, and in the path of the cavities 5.

An orfice 54, in series with the conduit 41 and 44 and the opening 48 is shown diagrammatically intermediate the ends of the conduit 44. An orfice 55 in the conduit 45 is in series with the conduit 41 and 45 and the hole 46.

In the operation of the hydraulic system illustrated in FIGURE 6, as the pinion 2 is rotated with the shaft 3, its eccentricity with respect to the ring gear 4 and the fact that there are different numbers of teeth on the ring gear and pinion produce expanding cavities through the length of the intake manifold, and contracting cavities through the length of the discharge manifold. By virtue of this arrangement, oil is pulled into the cavities 5 along the intake manifold at low pressure and forced out of the cavities along the discharge manifold at relatively high pressure. The oil from the discharge manifold 7 is forced through the conduit 39 into the chamber 38 between the iston and the seat. The pressure thus built up, causes the piston 34 to move, against the bias of the spring 36, away from the seat 31, and this permits the oil to escape through the passage 32, and also as the piston 34 begins to clear the port 40, to move through the conduit 41 to the chamber 42, to the branch conduits 44 and 45, and to the pump seal 43.

The restriction of the orifice 55 in the branch conduit 45 is sufficient to cause a marked pressure differential between the pressure in the intake manifold and the pressure in the conduit 41, which is reflected in the pressure in the branch conduit 44. This pressure, and the small amount of oil required to maintain it, are supplied, through the orifice 54, to the opening 48 in the land 8, hence to the cavity 5 as it passes across the face of the land 8.

Two things are to be noted: first, that the distance from the edge of the opening 48 closest to the discharge manifold 7 is slightly greater than the distance from crest to to crest of the teeth of the pinion 2, so that the opening 48 is never in communication with the discharge manifold 7; and second, that the opening 48, through the branch conduit 44, conduit 41, and branch conduit 45 is always in communication, as is the conduit 41, with the intake manifold 6.

With this arrangement, dangerously high pressures can never build up in the cavity 5 while it is along the land 8, but, at the same time, the pressure in the cavity will be built up to a pressure intermediate the pressure in the intake manifold and that in the discharge manifold. This aids greatly in preventing cavitation, and extends the range of pressure differentials which can be maintained between the intake and discharge manifolds.

Referring now to FIGURES l5 for the preferred commercial embodiment, reference numeral indicates a hydraulic system assembly including a pump 101, a pressure regulating and cut off valve assembly and an electric motor 160. In this embodiment, the motor 160 has an end shield 161 with a heavy central boss 162 which on its inside end contains a shaft seal gland 163 through which a rotor shaft 164 extends, and at its outside end forms a part of the casing of the pump 101. For this purpose, the outside end of the boss section of the end shield is milled to provide a race for a ring gear 1.04 and a fiat, radial, bearing and sealing surface containing balancing manifolds 116 and 117. A radial face 166 surrounding the race section is machined fiat, except for an O-ring groove it it.

The remainder of the pump casing is supplied by and in a heavy section of wall of the casing of the valve assembly 130. This pump casing part includes a planar face area 112, which fits in face to face relation with the flat area 156 on the end shield 161. An O-ring in the fiat area 166 serves as a seal as shown in FIGURE 1. The face 112 is interrupted by an intake manifold 106, and a discharge manifold 107, and by a shaft well 113 through the bottomdefining wall of which a gland hole 143 extends. Between the suction manifold 106 and the discharge manifold 107, the plane surface 112 defines a land 108, and between the discharge manifold 107 and the suction manifold 106 the surface 112 defines a land 109. The intake and discharge manifolds 106 and 107 face the balancing manifolds 116 and 117, but the latter end short of the former, to ensure that no short-circuiting occurs.

An intake port 126 in the intake manifold 106 communicates, by means of a conduit and fitting not here shown, with a source of fuel oil, also not here shown. A discharge port 137 communicates with the discharge manifold 107, and, through a passage 139, with a chamber 138 in the valve assembly.

A conduit opening 148, through the face of the land 108, communicates with one end of an orifice groove 155, the other end of which groove communicates With the intake manifold 106. The conduit opening 148 communicates with a conduit 144, which, in turn, communicates with a conduit 141, defined by an L-shaped channel in the valve casing and an inside surface of a casing cover plate 180. The conduit 141 communicates with a port which opens into the chamber 138 when a piston 134 moves down as is explained hereinafter to uncover it, and with a passage 147 which opens into a chamber 142 below the piston 134. The chamber 142 also communicates, through the seal gland passage 143, with the seal gland 163.

Within the valve assembly 130, a valve head 133, carried by the piston 134, is biased toward seating position against a seat 131 by a coil spring 136.

Within the pump 101, a pinion 102, keyed to the shaft 164, and a ring gear 104, journaled in the raceway in the outer face of the boss 162, correspond in every way with the pinion and the ring gear 2 and 4 of the embodiment shown in FIGURE 6.

Referring to FIGURES 36, it will be observed that the orifice groove of the embodiment shown in FIG- URES 3, 4 and 5, in series with the conduit opening 148 and the intake manifold 106, takes the place of orifices 54 and 55, conduit 45 and inlet bleeder hole 46 of the embodiment illustrated in FIGURE 6.

In the operation of the embodiment shown in FIG- URES 1-5, when the motor is started, the rotation of the pinion 102 and gear 104 act to pump fuel oil through the discharge port 137 and conduit 139 into the chamber 138. The pressure of the oil causes the piston 134 to move against the bias of the spring 136, uncovering a passage 132 to a nozzle, not here shown, and also uncovering the port 140, permitting oil to pass through the conduit 141 to the chamber 142 and seal gland 163, as well as to the conduit opening 143 in the face of the land 108. The opening 148 is always in communication, through the orifice groove 155, with the intake manifold 106. The opening 148 is spaced from the closest edge of the discharge manifold 107 just far enough so that the conduit opening 148 is never in communication, through a cavity, with the discharge manifold 107. Except for the instant at which the cavity opens into the discharge manifold 107, the opening 148 remains in communication with the cavity between the intake manifold 106 and the discharge manifold 107. This is illustrated in FIGURES 3 and 4. The restriction of the orifice groove 155, closed to form an orifice by a radial face of the ring gear 104, as shown in FIGURE 4, assures that, by the time the cavity moving past the land 108 reaches the position shown in FIGURE 4, it has reached a pressure substantially higher than the pressure in the intake manifold, though not as high as that in the discharge manifold.

The provision of oil under a positive pressure in the seal gland 163 also ensures that no air is pulled into the pump through that gland.

Numerous variations in the construction of the system of this invention, within the scope of the appended claims, will occur to those skilled in the art in the light of the foregoing disclosure.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. A hydraulic system comprising a rotary pump having an intake manifold, a discharge manifold, a land between said intake and discharge manifolds, a land between said discharge and intake manifolds and rotating means contiguous the said manifolds and lands for defining undulating cavities in a fixed pattern, a conduit opening at one end into the path of said cavities through the face contiguous the rotating means of the land between the intake and discharge manifolds and communicating at its other end mediately with the discharge manifold, and an orifice communicating at one end with said conduit and at its other end with said intake manifold, said orifice comprising a groove in the face of the land, communicating at one end directly with the conduit opening in the face of the land and at the other end directly with the intake manifold, said conduit opening through said land at such a position with respect to the discharge manifold that no cavity communicates simultaneously with the conduit and the discharge manifold.

2. A hydraulic system comprising a rotary pump having an intake manifold, a discharge manifold, a land between said intake and discharge manifolds, a land between said discharge and intake manifolds and rotating means contiguous the said manifolds and lands for defining undulating cavities in a fixed pattern, a conduit opening at one end into the path of said cavities through the face contiguous the rotating means of the land between the intake and discharge manifolds and communicating at its other end mediately with the discharge manifold, and an orifice communicating at one end with said conduit and at its other end with the said intake manifold, said orifice being connected in parallel with the said conduit, said conduit opening through said land at such a position with respect to the discharge manifold that no cavity communicates simultaneously with the conduit and the discharge manifold.

3. The hydraulic system of claim 2 wherein a second orifice is connected in series with said conduit.

References Cited UNITED STATES PATENTS 2,649,739 8/1953 Huiferd et a1. 103-126 2,805,628 9/1957 Herndon et al 103-126 2,820,416 1/1958 Compton 103-126 2,898,862 8/1959 Brundage 103-126 2,956,506 10/ 1960 Brundage 103-126 2,956,512 10/1960 Brundage 103-126 3,002,461 10/1961 Eames 103-42 3,025,802 3/1962 Browne 103-42 3,174,408 3/1965 Miller 103-126 3,237,566 3/1966 Roenick 103-126 DONLEY .T. STOCKING, Primmy Examiner. W. I. KRAUSS, Assistant Examiner. 

1. A HYDRAULIC SYSTEM COMPRISING A ROTARY PUMP HAVING AN INTAKE MANIFOLD, A DISCHARGE MANIFOLD, A LAND BETWEEN SAID INTAKE AND DISCHARGE MANIFOLDS, A LAND BETWEEN SAID DISCHARGE AND INTAKE MANIFOLDS AND ROTATING MEANS CONTIGUOUS THE SAID MANIFOLDS AND LANDS FOR DEFINING UNDULATING CAVITIES IN A FIXED PATTERN, A CONDUIT OPENING AT ONE END INTO THE PATH OF SAID CAVITIES THROUGH THE FACE CONTIGUOUS THE ROTATING MEANS OF THE LAND BETWEEN THE INTAKE AND DISCHRAGE MANIFOLDS AND COMMUNICATING AT ITS OTHER END MEDIATELY WITH THE DISCHARGE MANIFOLD, AND AN ORIFICE COMMUNICATING AT ONE END WITH SAID CONDUIT AND AT ITS OTHER WITH SAID INTAKE MANIFOLD, SAID ORIFICE COM- 